Tanks are often used for storing and processing liquids, such as for municipal water treatment and delivery systems. Water storage tanks may be above ground, or may be buried underground. For underground water storage tanks, vents are often provided to the atmosphere to allow air flow into and out of the tank. For example, when the volume of water in tank is increased, displaced air may be vented to the atmosphere to prevent the pressure in the tank from increasing beyond acceptable limits.
The vents for water storage tanks are typically U-shaped pipes. The vent pipes may extend upwardly from the tank to above ground level, and then curve back towards the ground level, but still spaced a distance therefrom. The inlet of the vent pipe, and thus the inlet of the water storage tank, faces downwardly toward the ground.
A screen is often provided over the vent pipe inlet to prevent small animals from entering the pipe. However, the screen may easily removed, permitting access to the pipe inlet, such as by cutting, bending, or simply forcing it off. A hose or other insertion device could be placed into the pipe inlet, allowing the introduction of foreign matter, such as contaminants, into the water storage tank which can contaminate any water therein. Accordingly, there remains a need for protecting water in a water storage tank from contamination caused by introduction of contaminants into a vent pipe inlet through a hose or other insertion device.